[PD] message-creation and parsing questions

[David Merrill]

Hello pd-ers,
I'm still getting the hang of pd, and I'm currently using it to build 
the mechanism to run a perceptual experiment.  For each condition I want 
to read in values from a text file, play a tone, and record the result. 
 The parts I'm having trouble with are:

- how can I build up a message from parts?  for instance, the [writesf~] 
object responds to an "open" message with a single argument, like:
"open /tmp/output1.wav"
but I want to be able to iterate, and supply "output2.wav", 
"output3.wav" etc..  I have looked at the docs for the [pack] object, 
but I'm not sure that it can receive messages as input and pack them, or 
output it's result as a message - is that correct?  am I thinking about 
this in a wrong way?

- how can I parse a line of text such as: "output1.wav 440 500 1500" 
that I get from a [textfile] [bang] into its constituent parts 
(preserving the appropriate types)?

- (related to the above) is parsing a string different from parsing a list?

much appreciated!
-David Merrill